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Investigations of novel neodymium-iron-boron type magnets and effects of crystallographic texture.

机译：新型钕铁硼型磁体的研究和晶体织构的影响。

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摘要

Investigations of Shock Compacted (Neodymium-Iron-Boron) NdFeB powder and NdFeB powders blended with Al, magnets prepared with NdFeB using liquid phase sintering with Al, and modeling of the effect of crystallographic texture on an idealized Nd{dollar}sb2{dollar}Fe{dollar}sb{lcub}14{rcub}{dollar}B magnet are reported. The NdFeB powder used in this study was prepared using a powder metallurgical approach. The final density of shock compacted material is independent of shock pressure and dependent on the ductility of the phases present. At low shock pressures for NdFeB powder only, the NdFeB grains fracture. At higher pressures partial melting of NdFeB results in a higher {dollar}alpha{dollar}-Fe content. The Al blended material have higher post shock densities. The microstructure of NdFeB material prepared using Al as a liquid phase sintering agent consists of a matrix region of the hard magnetic tetragonal Nd{dollar}sb2{dollar}Fe{dollar}sb{lcub}14{rcub}{dollar}B grains with dispersed pockets of neodymium oxides and a reacted intermetallic pocket region. Two distinct intermetallic phases are observed: cubic Fe{dollar}sb3{dollar}Al and another unreported tetragonal intermetallic with an approximate composition of Nd{dollar}sb{lcub}11{rcub}{dollar}Fe{dollar}sb{lcub}55{rcub}{dollar}Al{dollar}sb{lcub}34{rcub}{dollar}. Complete reaction between Nd{dollar}sb2{dollar}Fe{dollar}sb{lcub}14{rcub}{dollar}B and Al is observed after sintering at 1050{dollar}spcirc{dollar}C for 12 hours. The Al spreads more extensively at lower sintering temperatures. The magnetic properties are controlled by the average composition of Fe{dollar}sb3{dollar}Al since this phase is ferromagnetically soft for Al contents {dollar}<{dollar}30 at.%. The samples sintered at low temperatures for short times have the best magnetic properties since the average Al content of Fe{dollar}sb3{dollar}Al exceeds 30 at.%. A Stoner-Wohlfarth approach was used to study the effect of crystallographic texture on an assembly of single domain size spherical, noninteracting Nd{dollar}sb2{dollar}Fe{dollar}sb{lcub}14{rcub}{dollar}B particles. For a two dimensional case, serious reductions in the coercivity occur if the average particle deviates more than 9{dollar}spcirc{dollar} from perfect c-axis texture. The remanence decreases almost linearly with poorer texture. These results indicate that for an ideal microstructure of noninteracting single domain size particles of Nd{dollar}sb2{dollar}Fe{dollar}sb{lcub}14{rcub}{dollar}B isolated in an nonmagnetic matrix, good c-axis alignment is crucial.
机译：冲击压实（钕铁硼）NdFeB粉末和与NdFeB混合的NdFeB粉末，使用Al进行液相烧结制备的NdFeB磁体的研究，以及结晶织构对理想Nd {dollar} sb2 {dollar}的影响的模型研究据报道，Fe {dollar} sb {lcub} 14 {rcub} {dollar} B磁铁。本研究中使用的NdFeB粉末是采用粉末冶金方法制备的。冲击压实材料的最终密度与冲击压力无关，并且取决于存在的相的延展性。仅在NdFeB粉末的冲击压力较低时，NdFeB晶粒会破裂。在较高的压力下，NdFeB的部分熔化会导致较高的{alpha}α{dollar} -Fe含量。铝混合材料具有更高的后冲击密度。以Al为液相烧结剂制备的NdFeB材料的微观结构由硬磁四方Nd {dollar} sb2 {dollar} Fe {dollar} sb {lcub} 14 {rcub} {dollar} B晶粒的基体区域组成。分散的钕氧化物袋和一个反应的金属间袋区域。观察到两个不同的金属间相：立方Fe {dollar} sb3 {dollar} Al和另一个未报告的四方金属间化合物，其组成大致为Nd {dollar} sb {lcub} 11 {rcub} {dollar} Fe {dollar} sb {lcub} 55 {rcub} {dollar} Al {dollar} sb {lcub} 34 {rcub} {dollar}。在1050℃下烧结12小时后，观察到Nd {sb2sb2 {USD} Fe {sdol} sb {lcub} 14 {rcub} B和Al之间的完全反应。在较低的烧结温度下，Al会更广泛地扩散。磁性由Fe {sdol3sb3 {dollar} Al的平均组成来控制，因为对于Al含量{dollar} ＜{dollar} 30at。％，该相是铁磁软的。由于Fe {dollar} sb3 {dollar} Al的平均Al含量超过30 at。％，因此在低温下短时间烧结的样品具有最佳的磁性。使用Stoner-Wohlfarth方法研究了晶体织构对单畴尺寸的球形非相互作用Nd {dollar} sb2 {dollar} Fe {dollar} sb {lcub} 14 {rcub} {dollar} B粒子组装体的影响。对于二维情况，如果平均粒子与理想c轴纹理的偏差超过9 {spcirc {dollar}，则矫顽力会严重降低。剩磁几乎随着质地较差而线性降低。这些结果表明，对于在非磁性基质中分离的Nd {dollar} sb2 {dollar} Fe {dollar} sb {lcub} 14 {rcub} {dollar} B的非相互作用单畴尺寸颗粒的理想微观结构，良好的c轴对准至关重要。

著录项

  • 作者

    Chandramouli, Mahesh.;

  • 作者单位

    University of California, Berkeley.;

  • 授予单位 University of California, Berkeley.;
  • 学科 Mineralogy.; Engineering Materials Science.
  • 学位 Ph.D.
  • 年度 1995
  • 页码 199 p.
  • 总页数 199
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 矿物学;工程材料学;
  • 关键词

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